Electroplating of nickel

ABSTRACT

AN AQUEOUS ACIDIC NICKEL PLATING BATH WHICH CONTAINS A BRIGHTENING AMOUNT OF A COMPOUND HAVING THE FORMULA:   2-(O=),3-(R-CH=),R1,R2-2,3-DIHYDROBENZOFURAN   WHEREIN R1 AND R2 ARE H, CH3, C2H5, F, CL, BR, CH3O-, C2H5O-, CH3CO-, CH3CONH-, -(CH2)N-SO3H, -O(CH2)N-SO3H, C2H5CONH-. R IS H, F, CL OR PHENYL, AND N IS A NUMBER FROM 1 TO 6 INCLUSIVE.

United States Patent Office 3,770,730 Patented Nov. 6, 1973 U.S. Cl. 260-240 F 7 Claims ABSTRACT OF THE DISCLOSURE An aqueous acidic nickel plating bath which contains a brightening amount of a compound having the formula:

O(CH ),,SO H, C H CO, or C H CONH. R is H, F, Cl or phenyl, and n is a number from 1 to 6 inclusive.

This is a division, of application Ser. No. 124,941, filed Mar. 16, 1971 now U.S. Pat. 3,663,378 issued May 16, 1972, which is a continuation-in-part of U.S. Ser. No. 812,377 filed Apr. 1, 1969, now abandoned.

This invention relates to the electrodeposition of semibright, or bright, sulfur-free, high leveling nickel plate from aqueous acidic nickel plating baths and more particularly, it relates to the use of an addition agent as an improved brightener in acidic nickel plating baths.

Heretofore, numerous brightenings agents have been proposed for acidic nickel plating baths. Among those which have been successfully used commercially are coumarin and its various derivatives. Although coumarin does produce good leveling and allows the formation of a semi-bright sulfur-free nickel plate of high ductility, the nickel plate produced is not as passive as is often desired. Similarly, while the unsaturated esters, such as dimethyl fumarate, dimethyl maleate, dimethyl itaconate, trimethyl aconitate and the like also produce a leveling nickel plate of high ductility, they hydrolyze in the plating bath, merely on standing, to give harmful products which cause dulling of the plate and decrease the leveling.

It is, therefore an object of the present invention to provide an acid nickel plating bath containing an improved brightener which overcomes these difficulties.

Another object of the present invention is to provide an improved process for electroplating a ductile, lustrous nickel plate.

These and other objects will become apparent to those skilled in the art from the description of the invention which follows:

Pursuant to the above objects, the present invention includes a bath for electroplating ductile, lustrous nickel plate which comprises an aqueous acidic nickel plating solution containing at least one soluble nickel plating salt and a brightening amount of a compound having the formula:

-(CH SO H or O(CH ),,SO H. R is H, F, Cl or phenyl, and n is a number from 1 to 6 inclusive.

More specifically, in the practice of the present invention, the plating bath is an aqueous acidic nickel plating solution which contains at least one soluble nickel plating salt, desirably selected from nickel sulfate, nickel chloride, nickel bromide, nickel sulfamate and nickel fluoroborate, and a brightening amount of a compound falling within the Formula A given above. Preferably, the compound used has the following structure:

:0 \O/ (B) In such baths these compounds are present in amounts which will provide brightening and leveling of the nickel plate produced, amounts within the range of about 0.03 to l gram/liter being desired, with amounts within the range of about 0.1 to 0.3 gram/liter being preferred.

The brightening additives of the present invention may be prepared, generally, by condensing the lactone of an o-hydroxy phenyl acetic acid with an aldehyde. Such preparation is illustrated specifically with regard to the preparation of compound (B) above. In this preparation, the lactone of o-hydroxy phenyl acetic acid is condensed with formaldehyde, as follows:

(in, o=onl C=O 0:0 0:0 +1120 H \O/ Other compounds falling Within Formula. A may be similarly prepared by using other aldehydes and/or derivatives of the lactone of o-hydroxy phenyl acetic acid. For example, benzaldehyde may be used in place of formaldehyde in the above reaction to produce an additive having a phenyl substituted vinyl group. Similar reactions may be carried out using o-hydroxy phenyl acetic acid lactones having substituting groups on the benzene ring such as fluoro, chloro, bromo, methyl, methoxy, ethyl, ethoxy, acetyl, acetylamino, propionyl, propionylamino, and sulfoalkyl, or sulfoalkylether groups where the alkyl group is not more than 6 carbons. It is preferred, however, that not more than two such groups be present on the benzene ring.

The starting materials for the above reaction are prepared according to the preparations described in Organic Syntheses, Collective, vol. III, John Wiley (1955), pp. 715, et seq. In general an aldehyde, such as formaldehyde or benzaldehyde is reacted with (D) HOC H -CH CN in the presence of sodium ethoxide. The lactone is formed by acidifying the product of the preceding reaction.

In place of (D), the halogenated materials may be used such as the fluoro, chloro, abromo. Likewise the alkyl (methyl and ethyl), alkoxy (methoxy and ethoxy) and ketones (methyl and ethyl ketone) are used in place of (D) in the reaction sodium ethoxide.

The NHC0CH and NHCOC H substituted materials that are to be used in place of (D) in the reaction with sodium ethoxide are prepared by reacting the amine precursor with CH COCl or C H COCl as follows:

0 H NH CHK JN OH OH CHzCO C1 CH2CN CH2CN The --(CH -SO H materials are prepared by reactmg:

' CH3(CH2)nC1 NaHSO NC CH:-

The O(CH SO H materials are prepared by reacting:

N5 Cl(CH SO H NC CH The preparation of the compounds where R is chloro o r t1iluoro is as follows. Hydrogenate, the double bond of e1 er The hydrogenated compound is then reacted with chlorine to replace two hydrogen atoms with two chlorine atoms and then dehydro-halogenated. If need be the product may be acidified to insure the presence of the lactone.

The fluorinated materials (where R is F) are prepared by substituting chlorine with fluorine in the presence of SbF according to the Swartz reaction.

As has been noted previously, the aqueous acidic nickel plating baths may be of various types, including the Watts type or modifications thereof. The nickel salts used in formulating the baths are desirably nickel sulfate, nickel chloride, nickel bromide, nickel sulfamate, nickel fluoborate, as well as mixtures of any two or more of these. In many instances the nickel salts are preferably used in conjunction with bufler materials, such as boric acid. Other acidic type buffers which may be used include formic acid, fluoboric acid, and the like, and these may be used either in place of or in conjunction with boric acid. It has generally been found that optimum results are obtained when the concentration of the boric acid, or its equivalent, is at least about 30 grams/liter.

Compound (A) may be used in concentrations of 0.05 to 1 gram per liter, preferably 0.1 to 0.3 g./l., when used alone in the baths, especially Watts nickel baths, or dilute all chloride (about 100 g./l. NiCl .6H O) nickel baths. When used alone in such baths it allows the production of ductile, high leveling sulfur-free nickel plate. It also cooperates excellently with small concentrations, 0.001 to 0.2 g./ 1., of one or more of the following non-sulfur containing compounds: formaldehyde, chloral hydrate, bromal, coumarin, butyne diol, and the monoand diethylene oxide and propylene oxide adducts of propargyl alcohol and allyl alcohol, and the mono-1,3-dioxolane adduct of butyne diol, propargyl alcohol and allyl alcohol, in the production of semi-bright high leveling sulfur-free ductile nickel plate. I

If o-benzoyl sulfimide and/ or other class I nickel brightners (benzene sulfonamide, naphthalene trisulfonic acid, propargyl sulfonic acid, and the like) are used in conjunction with (A) in acidic nickel baths (sulfate, chloride, bromide, fluoborate, sulfamate), full bright nickel plate is obtained. It is preferred, however, to use compound (A) in the deposition of semi-bright high leveling, sulfur-free nickel plate.

Examples of typical preferred embodiments of the nickel plating baths of the present invention are given below. These baths are aqueous solutions containing the listed components in the amounts indicated.

4 EXAMPLE I G./l. NiSO .6H 0 150-300 NiCl .6H O 0-40 H BO 40 Compound (B) 1 003-06 Temp. 50-60" C., pH 4-5, air agitation.

1 0.1-0.3 preferred.

The presence of the low foaming wetting agent 2-ethyl hexyl sulfate (sodium salt) is desirable, in concentrations of 0.1 to 0.5 g./l.

When no nickel chloride is used, sulfur containing anodes (S D nickel) are to be used which dissolve anodically without the presence of chloride ions in the bath. If cathode rod agitation is used instead of air agitation, sodium lauryl sulfate is a preferred wetting agent in concentrations of 0.05 to 0.3 g./l.

EXAMPLE 2 To the bath of Example 1, 2-10 mg./l. of the 1 to 1 mole 1,3-dioxolane adduct of propargyl alcohol or the 1 to 2 mole propylene oxide adduct of propargyl alcohol are added, thus making it possible to use slightly lower optimum concentrations of compound (B) in the bath, that is 0.1 to 0.2 g./l. instead of 0.2 to 0.6 g./l.

EXAMPLE 3 To the bath of Example 1, 20 mg./l. of formaldehyde and 30 to 50 mg./l. of chloral hydrate are added, thus making it possible to use slightly lower concentrations of the compound (B).

An example of fully bright plating nickel bath is shown in Example 4 below. Instead of o-benzoyl sulfimide, p-toluene sulfonamide and the other well known class I nickel brighteners shown in U.S. Pat. 2,781,306, col 6, Table II may be used.

Air agitation-If mechanical or cathode rod agitation is used, then sodium lauryl sulfate wetting agent, in concentrations of about 0.1 to 0.5 g./l. is preferred over the shorter chain similar surfactants.

The electroplating baths of the preceding examples may be operated at temperatures from about room temperature to almost boiling, with temperatures within the range of about 40 to 60 0. being preferred. The pH values of these baths may range from about 2 to 5.5, although pH values within the range of about 3.0 to 4.8 are preferred. The cathode current densities used may also vary, values within the range of about 5 to several hundred amperes/square foot being useful. While the preferred range is about 20 to amperes/square foot, the optimum will depend in each instance on the agitation, temperature, and concentration and type of nickel salts used in the bath.

When the plating baths of the present invention are operated in accordance with the above procedure, it is found that the compounds having the Formula A are outstanding nickel brighteners and there is produced an excellent semi-bright or full bright, sulfur-free high leveling nickel plate. A more passive plate is produced than with coumarin and the compounds (A), do not hydrolyze in the warm acid nickel plating baths, forming harmful products which cause dulling of the plate and decrease leveling, as do the unsaturated esters such as dimethyl itaconate, and the like.

While there have been described various embodiments of the invention, the compositions and methods described are not intended to be understood as limiting the scope of the invention as changes therewithin are possible and it is intended that each element recited in any of the following claims is to be understood as referring to all equivalent elements for accomplishing the same results in substantially the same or equivalent manner, it being intended to cover the invention broadly in whatever form its principle may be utilized.

What is claimed is:

1. A compound of the formula:

R1 C=CHR R o=o wherein R and R are independently selected from the group consisting of H, C(O)CH -C(O)C H NCH(O)CH NHC(O)C H -(CH ),,4O H and provided at least one of R and R is other than H; R is independently selected from the group consisting of hydrogen, fluoro, chloro, and phenyl; and n is a number from 1 to 6 inclusive.

6 2. The compound of claim 1 wherein R and R are independently selected from the group consisting of ll u -0 CH3 and C 02115 3. The compound of claim 1 wherein R and R are independently selected from the group consisting of if i -NHC OH! and NH0 C3115 4. The compound of claim 1 wherein R and R are independently selected from the group consisting of --(CH -SO H and O(CH SO H 5. The compound of claim 1 wherein R is hydrogen. 6. The compound of claim 1 wherein R is independently selected from the group consisting of F and Cl.

7. The compound of claim 1 wherein R is CH References Cited Czaplicki et al.: Ber. Dent. Chem, vol. 42, pp. 827 to 838 (1909).

Gripenberg et al.: Acta. Chem. Scan., vol. 8, pp. 734- 737 (1954).

Molho et al.: Bull. Soc. Chim. France, 1954, pp. 1397- 1401.

Molho et al.: Bull. Soc. Chim. France, 1956, pp. 78 to 93.

Chemical Abstracts, Sixth Collective Index, Subject Index A-Bi, p. 579 s 1964.

JOHN D. RANDOLPH, Primary Examiner US. Cl. X.R. 

